ALL the stuff here is 13,200 V .............. Primary !
Walt K8CV Royal Oak, MI.
----- Original Message -----
From: "Gary Hoffman" <email@example.com>
To: "Discussion of Ten-Tec Equipment" <firstname.lastname@example.org>
Sent: Thursday, April 02, 2009 9:50 PM
Subject: Re: [TenTec] Corsair II buzz
> Hmmm....in our neighborhood we certainly have nothing remotely like a 240
> delta system serving residences, being center tapped and all as mentioned
> What we have are moderately high voltage lines - on my street they are at
> like 3400 volts, phase to phase. While three phases are available, only
> are run down my street, because that is all they need for our low power
> Local transformers, that service a couple of houses each, pick off power
> from these two primary phases, and produce a center tapped 240 V AC
> If there were a buzz around here, it sure would not be due to the source
> ----- Original Message -----
> From: "Jim Brown" <email@example.com>
> To: <Gary@doctorgary.net>; "Discussion of Ten-Tec Equipment"
> Sent: Thursday, April 02, 2009 9:13 PM
> Subject: Re: [TenTec] Corsair II buzz
>> Gary Smith wrote:
>>> I have noticed the "buzz" on several different power supplies
>>> including a deep cycle battery. It's definitely not a hum but sounds
>>> like something with odd harmonics, a definite buzz.
>> The most common source of "buzz" consists of "triplen" harmonics of the
>> AC power line, coupled from the 3-phase power line that is probably
>> providing your residential service. See my recommendations for bonding
>> together the gear in your station to kill this noise. Triplen harmonics
>> are harmonics whose orders are divisible by three -- 180 Hz, 360 Hz, 540
>> Hz, and so on.
>> http://audiosystemsgroup.com/RFI-Ham.pdf and
>> The first one is a tutorial in text form that covers a lot of material,
>> including this. The second is a Power Point that covers much of the same
>> My solutions are very simple and inexpensive, and don't involve going
>> inside the radio.
>> These harmonics are produced in power systems by current flowing at the
>> peak of the cycle to charge the input filter capacitors in electronic
>> power supplies (both linear and switchers). Most current cancels in the
>> neutral (and in the green wires) of 3-phase systems, but triplen
>> harmonics add. So-called "high leg Delta" power distribution is widely
>> used in neighborhoods where a few small users need 3-phase but most need
>> 120/240V. It's a 240V Delta, but with one side being center-tapped to
>> feed residences. This triplen current is the source of what we call
>> "ground buzz." It's there because there's no neutral feed to those
>> 3-phase users, so all their triplen current goes to ground in the
>> neutral for residences!
>> This is yet another reason why it's a very good thing to bond all
>> grounds together (the most important being lightning). To learn more see
>> the tutorials.
>> Jim Brown K9YC
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